Selection techniques of commonly used valves in chemical design

Valves are widely used in pipeline systems in chemical engineering design, which can directly affect the operation of pipelines and determine the actual effect and safety of pipeline operations. Therefore, choosing the right type of valve has become the primary consideration factor for chemical companies to select valves. In order to ensure the rationality of chemical design, it is necessary to study the valve selection principles and techniques.

1, the importance of valve selection

The continuous development of science and technology has led to a significant increase in the types of valves. As far as the valves commonly used in chemical companies are concerned, mainly for pressure reducing valves, emergency shut-off valves, throttle valves, check valves and gate valves, etc. The points are different. Some chemical products in the production process, due to neglecting the valve type and material selection, resulting in low production efficiency and even major safety accidents, through analysis can be found mainly because the key points of valve selection are not grasped. By comprehensively considering the chemical production requirements and the characteristics of the valve, it is necessary to first determine the applicability when selecting the valve, and ensure that the switch operation mode and working pressure of the valve are completely matched with the needs of the chemical equipment. When selecting different types of valves, it is necessary to determine which type and material of the valve to use according to the characteristics, advantages and disadvantages of the different valves and application conditions. At the same time, the valve port connection application needs to be considered.

2, the type of commonly used valves

2.1 stop valve

The shut-off valve is a downward-closed valve. The valve stem is a power device that can drive the valve to move in a specific trajectory to achieve the adjustment. The shut-off valve has a simple structure, low price and convenient maintenance, and is widely used in chemical pipelines. At the same time, the shut-off valve also has some shortcomings, such as poor regulation performance, special requirements for the medium, and greater energy consumption when the valve is opened and closed.

2.2 throttle valve

The throttle valve is a throttling element commonly used in chemical production. The main functional component is the valve flap, and the rest of the structure is roughly the same as the shut-off valve. The advantages and disadvantages of the throttle valve can be referred to the shut-off valve.

2.3 gate valve

The main components of the gate valve are the valve stem and the valve plate, and the valve plate will be lifted and lowered by the valve stem. Although the gate valve has good airtightness and strong adjustment function, its large size, complicated structure and long maintenance time are extremely limited in the application of chemical systems.

2.4 butterfly valve

The butterfly valve controls the switch under the action of vertical rotation, and mainly plays the role of cutting and intercepting in the pipeline. The butterfly valve has a simple structure, strong adaptability to the environment, and an ideal control effect.

2.5 plug valve

The plug valve is driven by the valve stem to rotate the plug body to achieve the purpose of opening and closing the pipeline, and has the advantages of good sealing, sensitive control, fast reaction speed and low working noise.

2.6 Diaphragm valve

The construction and working principle of the diaphragm valve are obviously different from those of other valves. The rubber membrane and the plastic membrane are used to realize the control function. The pipeline medium using the diaphragm valve must contain hard suspended matter, and there are certain restrictions on the pipeline pressure. .

2.7 check valve

The check valve can keep the pipeline medium flowing in a single direction, prevent the medium from flowing backwards, is suitable for corrosive medium and high pressure pipelines, and can also be used in chemical sewage treatment systems, and has high economic value and practical value.

3, different types of valve selection principles

For the current classification of valves and complex working conditions, to select the valve products with the right type and material, it is necessary to master the characteristics of the valve, and choose the steps, basis and use principle of the valve selection. The valve selection principle is as follows: For straight-through valves with small flow resistance, they are mostly used as valves for open and cut-off media; if you want to control the flow, you can choose the valve to adjust the flow; if it is used for commutation, you can use Ball valve and plug valve; if for medium with suspended particles, a valve with a wiping action of the closing member along the sealing surface can be used.

4. Selection techniques of commonly used valves in chemical design

4.1 Defining the function of the valve and positioning the valve

In the design of chemical pipelines, for the valves involved in the pipelines, it is necessary to have a clear function to locate the use of the valves. In this case, it is necessary to further clarify the functions to be played for the selected valves, and at the same time Understand the control mode, working pressure, etc. of the selected valve, and familiarize with the function of the selected valve, and then select the appropriate valve according to the actual situation of the chemical pipeline to a certain extent.

4.2 familiar with the characteristics of the valve

In the valve market, due to the different functions of the valves, there are certain differences in the types of valves. For different types of valves, whether it is characteristics, production or application, there will be more or less certain differences. Based on this, in the design of chemical pipelines, it is necessary to consider the characteristics of the valves. The type of valve selected avoids the use of unreasonable valves, which in turn affects the safety and reliability of chemical pipeline operation.

4.3 Valve port consistency

In the process of chemical design, when selecting the valve, it is necessary to pay attention to the consistency of the valve port, and ensure that the selected valve can be connected normally, thus effectively ensuring that the valve fully exerts its role in the chemical design process.

4.4 pay attention to the quality of the selected valve

In order to ensure the normal operation of the chemical pipeline, in the design of the chemical process, it is necessary to attach great importance to the quality of the selected valve, to strictly control the material of the valve, and to effectively control the quality of the valve due to material problems. Ensure that the chemical pipeline can operate normally. In addition, in the selection of the valve, it is necessary to complete a comprehensive analysis of the valve flow and pressure and other factors to prevent the use of the valve.

5. Selection strategy of commonly used valves in chemical design

After mastering the selection techniques of common valves, apply them to chemical design practice to improve the advanced and scientific nature of chemical design. In the selection of valves for chemical design, the gate valve is usually given priority. This is because the switch control of the gate valve is widely used. It can be used in pipes with steam or oil as well as other media. Moreover, the gate valve has advantages in application in chemical production and chemical system operation, which are unmatched by other valves. In the chemical design, the selection of the shut-off valve should first be considered from the scope of application of the shut-off valve. The shut-off valve is suitable for some chemical pipelines that are not strict with the fluid resistance requirements, especially small in the chemical pipeline. The valve can be optionally used with a shut-off valve. The shut-off valve can be used to regulate pipe flow and pipe pressure, but the adjustment accuracy is not high. Throttle valves are generally used in environments where the temperature and pressure of the medium are high. They are often used in the regulation of flow and pressure. It should be noted that the throttle valve cannot be used as a block valve in chemical design. In addition, in the chemical design, when the plug valve and the butterfly valve and the check valve are selected for use, they should be scientifically and rationally selected and applied according to the respective applicable scopes and the application characteristics of the valve.

Conclusion

All in all, the selection of valves for chemical design not only determines the application value of the design, but also closely related to chemical production. When selecting common valves, it is necessary to strengthen the collection of valve data, scientifically analyze the relevant information of chemical systems and valves, and develop The perfect valve selection scheme ensures that the valve is of good quality and reasonable application, and can fully exert the adjustment and control functions, thus providing a safe and reliable environment for chemical production.